The concept of breeds is a relatively recent one. A breed is not the same as what is called a landrace. The latter is a genetic stock in a particular area which has adapted over the centuries to the local conditions. A breed has been bred in controlled conditions, with documentation in the form of a herd book. One can become the other; for example, Highland cattle prior to the mid-19th century were a landrace, but more recently have become a breed (herd book established 1885).
Some breeds have been enormously influential because used for the establishment or improvement of herds far from their native lands. British breeders have been to the fore in all this, and British bulls have been among Britain’s most important exports. The breeds whose genes are most widely distributed include:
dairy breeds: Dairy Shorthorn, Jersey, Swiss Brown, Friesian/Holstein.
beef breeds: Beef Shorthorn, Hereford, Aberdeen Angus, Devon.